No way to call external programs -- and pipe into/from them?
jpellegrini opened this issue · comments
Hello,
I see that currently Foment has no support for executing external binaries and piping data into or from them. It would benice if we could, for example, do this (the with-input-from-pipe procedure below is Chicken-specific):
(with-input-from-pipe
"iptables -L"
(lambda ()
(read-string #f))))
I do not know how difficult it would be to implement this portably in Foment.
This looks interesting; let me see what I can do. I see that Chicken has a processes module and Chibi has a processes module.
Do you have a preference for a particular API?
This looks interesting; let me see what I can do. I see that Chicken has a processes module and Chibi has a processes module.
Do you have a preference for a particular API?
I see that there is no SRFI for that. Perhaps it would be nice to have part of Chicken's API -- not necessarily all of it? For example,
process-execute
process-fork
process-run
process-signal
process-wait
process-sleep
process
process*
but not create-session. Or maybe a subset of the above. What do you think?
The Chibi API doesn't seem too different, conceptually...
After implementing part of Chicken's API, I decided to use Racket's Processes API instead. I found it to be cleaner and much more platform agnostic. It should be possible to implement the process convenience procedures (eg. with-input-from-pipe) on top of it.
I have done an initial implementation of the subprocess APIs on the processes branch for Mac OSX if you are interested in taking a look.
(call-with-values
(lambda () (subprocess #f #f 'stdout "/bin/ls" "-lh"))
(lambda (sub in out err)
(define (read-all port)
(let ((s (read-line port)))
(if (not (eof-object? s))
(begin
(display s)
(newline)
(read-all port)))))
(read-all in)))
That's great!
I compiled it on Linux, BTW, and it worked on a x86 desktop. The only changes necessary were these three lines
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
inside the #ifdef FOMENT_UNIX block.
Will compile and test on a MIPS machine soon.
The only changes necessary were these three lines
#include <stdlib.h> #include <sys/types.h> #include <sys/wait.h>inside the
#ifdef FOMENT_UNIXblock.
I meant in process.cpp, of course...
The Processes API is done for Linux and Mac OS. I still need to implement support for Windows.
The code is on the processes branch; I will merge it into master once I have Windows support done.
As part of testing the code, I did sample implementations of call-with-input-pipe, call-with-output-pipe, with-input-from-pipe, and with-output-to-pipe.
Thank you! Foment now will work fine as a scripting language!
Windows is done as well; Processes API has been merged into the master branch.